With the development of mobile communication technologies, people are no longer satisfied with a communication mode of only voice communication. They require a brand-new multimedia communication. The multimedia communication is more than simple audio and video communication, but incorporates instant messaging, collaborative work, and streaming media, especially the convergence of new communication with traditional voice communication. According to the trend of Internet and telecom network convergence, standardization organizations have proposed the concept of next generation networks. The Third Generation Partnership Project (3GPP) introduces an IP multimedia subsystem (IMS) core network with all Internet Protocol (IP) service network architecture on the basis of a packet bearer network. The purpose of the IMS is to control the openness of service capabilities regardless of user access modes and to provide multimedia communication experience according to personalized user data. Video sharing means one user equipment (UE) shares local video information with other one or more UE. The video information for sharing includes video clips taken by a camera, local video files, images, music clips and flashes.
The signaling control of video sharing is based on the Session Initiation Protocol (SIP). Before an originating user equipment (UE) can share video information with a terminating UE, the originating UE and the terminating UE must register with the IMS core network. Video sharing may be between a broadband mobile network and a non-broadband mobile network, or between two non-broadband mobile networks. Broadband mobile networks include networks compliant with 3GPP R5 or later 3GPP releases, in which the calls are carried over IP. Non-broadband mobile networks include networks compliant with the 2.5 Generation (2.5G), 3GPP R99, and 3GPP R4, in which basic calls are carried over the circuit switched (CS) domain and data services are carried over the general packet radio service (GPRS) system.
FIG. 1 shows a conventional method for video sharing where the originating UE is a UE in a broadband mobile network and the terminating UE is a UE in a non-broadband mobile network. The originating UE communicates with a originating application server (AS) via an originating IMS core network. The originating AS communicates with a terminating AS via the originating IMS core network and a terminating IMS core network. The terminating AS communicates with the terminating UE via the terminating IMS core network. For the purpose of description, the method below only deal with the originating UE, the originating AS, the terminating AS and the terminating UE.
As shown in FIG. 1, the method for video sharing includes the following steps:
Steps 101-106: The originating UE and the terminating UE perform media negotiation on the basis of SIP.
Specifically, the originating UE sends a video sharing invitation to the terminating UE via the originating AS and the terminating AS; the terminating UE sends the media negotiation result to the originating UE via the terminating AS and the originating AS.
Steps 107-130: The originating UE and the terminating UE establish provisional communication.
Specifically, the process includes: the originating UE sends a Provisional Response Acknowledgement (PRACK) to the terminating UE via the originating AS and the terminating AS; the terminating UE sends an acknowledgement to the originating UE via the terminating AS and the originating AS; the originating UE sends an UPDATE to the terminating UE via the originating AS and the terminating AS; the terminating UE sends an ALERT to the originating UE via the terminating AS and the originating AS; the originating UE sends a PRACK to the terminating UE via the originating AS and the terminating AS; the terminating UE sends an acknowledgement to the originating UE via the terminating AS and the originating AS; the terminating UE sends a video sharing acknowledgement to the originating UE via the terminating AS and the originating AS; the originating UE sends a response acknowledgement to the terminating UE via the originating AS and the terminating AS.
Steps 131-134: The originating UE and terminating UE establish a Real-Time Transport Protocol (RTP) link and share video information.
Specifically, the process includes: the originating UE establishes an RTP link with the terminating UE; the terminating UE sends a receiver report to the originating UE; the originating UE sends a sender report to the terminating UE; the originating UE shares video information with the terminating UE over the RTP link.
Steps 135-141: The terminating UE terminates the video sharing, the originating UE and terminating UE release the communication link, and the video sharing ends.
Specifically, the terminating UE sends an RTP LINK RELEASE message to the originating UE; the terminating UE sends a RELEASE message to the originating UE via the terminating AS and the originating AS; the originating UE sends a RELEASE ACK to the terminating UE via the originating AS and the terminating AS.
In the prior art shown in FIG. 1, the UE in a non-broadband mobile network needs to activate a GPRS connection after power-on and register with the IMS core network, and the UE in a broadband mobile network registers with the IMS core network automatically after power-on. Before a UE in any network registers with the IMS core network, the UE is unable to share video information with UEs in other networks. After successful registration, the UEs establish a connection and perform media negotiation over SIP and transfer the shared media according to the negotiation result.
If the terminating UE is in a non-broadband mobile network, its GPRS connection is normally inactive and the control signaling of the originating UE in a broadband mobile network cannot be routed correctly to the terminating UE. To ensure correct routing of control signaling, the UE in the non-broadband mobile network must be always GPRS activated and IMS core network registered. This will consume a large quantity of resources in the PS domain. Besides, to keep the GPRS connection active increases the energy consumption of the UE and shortens its standby time.
FIG. 2 illustrates a method in the prior art for implementing video sharing between two UEs in a non-broadband network. The originating UE communicates with the originating AS via the originating IMS core network. The originating AS communicates with the terminating AS via the originating IMS core network and the terminating IMS core network. The terminating AS communicates with the terminating UE via the terminating IMS core network. For the purpose of description, the method below only deals with the originating UE, the originating AS, the terminating AS and the terminating UE. According to FIG. 2, the method includes the following steps:
Step 201: The originating UE and the terminating UE establish a voice connection.
Steps 202-213: The originating UE and the terminating UE query whether the other party is capable of video sharing.
Specifically, the process includes: the originating UE sends a QUERY message to the terminating UE via the originating AS and the terminating AS; the terminating UE sends a QUERY ACK to the originating UE via the terminating AS and the originating AS; the terminating UE sends a QUERY message to the originating UE via the terminating AS and the originating AS; the originating UE sends a QUERY ACK_200 to the terminating UE via the originating AS and the terminating AS.
Steps 214-219: The originating UE and the terminating UE perform media negotiation on the basis of SIP.
Specifically, the process includes: the originating UE sends a video sharing request to the terminating UE via the originating AS and the terminating AS; the terminating UE sends the media negotiation result to the originating UE via the terminating AS and the originating AS.
Steps 220-246: The originating UE and the terminating UE establish provisional communication.
Specifically, the process includes: the originating UE sends a PRACK to the terminating UE via the originating AS and the terminating AS; the terminating UE sends an acknowledgement to the originating UE via the terminating AS and the originating AS; the originating UE sends an UPDATE to the terminating UE via the originating AS and the terminating AS; the terminating UE sends an ALERT to the originating UE via the terminating AS and the originating AS; the originating UE sends a PRACK to the terminating UE via the originating AS and the terminating AS; the terminating UE sends an acknowledgement to the originating UE via the terminating AS and the originating AS; the terminating UE sends a video sharing request acknowledgement to the originating UE via the terminating AS and the originating AS; the originating UE sends a response acknowledgement to the terminating UE via the originating AS and the terminating AS.
Steps 247-250: The originating UE and the terminating UE establish an RTP link and share video information over the link.
Specifically, the process includes: the originating UE establishes an RTP link with the terminating UE; the terminating UE sends a receiver report to the originating UE; the originating UE sends a sender report to the terminating UE; the originating UE shares video information with the terminating UE via the RTP link.
Steps 251-257: The terminating UE terminates the video sharing, the originating and terminating UEs release the communication link, and the video sharing ends.
Specifically, the process includes: the terminating UE sends an RTP LINK RELEASE message to the originating UE; the terminating UE sends a RELEASE message to the originating UE via the terminating AS and the originating AS; the originating UE sends a RELEASE ACK to the terminating UE via the originating AS and the terminating AS.
Step 258: The originating UE and the terminating UE restore the voice connection in the CS domain.
In the prior art shown in FIG. 2, the originating UE and the terminating UE first establish a voice connection in the CS domain. Both the originating UE and the terminating UE automatically activate the GPRS connection and register with the IMS core network so that video information can be shared between them.
Because the terminating UE does not need to be always GPRS activated and IMS core network registered, the terminating UE achieves lower energy consumption and uses fewer PS domain resources. Nevertheless, the method is subject to certain deficiencies. First, a voice connection must be established in the CS domain before video sharing. This causes certain restrictions to video sharing. Users may give up sharing due to the cost of the voice call. Second, most users establish voice connections for calls, and not for video sharing. When a GPRS connection is activated and registration is performed in the IMS core network for each voice call, there will be a waste of GPRS resources. Third, no matter whether the originating UE and terminating UE are IMS core network registered, video sharing is impossible without an established voice connection.